RFR: 8156499 Update jlink to support creating images with modules that are packaged as multi-release JARs

[Steve Drach]

>>> In JarArchive::entries then you filter out META-INF/MANIFEST.MF and I'm not sure that that is right (think modular JAR on the module path with a manifest, it's just a resource file).
>> I took that out and it still works as expected.
>> 
>>> Are directories the only case where toEntry can return null, in which case would it simpler to filter out directories here.
>> I’ve done that too.
>> 
>>> There is quite a bit of clean-up needed in this area (pre-dates your patch of course). Not clear why Archive isn't a Closeable for example, or why covariant returns aren't used by the more specialized JarArchive/JarEntry/etc. I'm sure you don't want to get into that but maybe we could at least make the JarFile available via a protected method rather than a field.
>> I’ve made JarFile available via a protected method
> This sounds good. Do you have an updated patch? (the current patch is webrev.03 and I couldn't find a webrev.04).
> 
> -Alan.

I’m going to update the test to use the new ToolProvider SPI, then I’ll put a new webrev out today.